The subject is realism. It involves seeing clearly your moment in time and where you are within it. We have a heck of a time with this. Our dreams, hungers and illusions get in the way.

But I’ve never seen such a lack of reality among our two great political parties in Congress.

Their own survival as parties requires bipartisanship—concrete achievements and progress. They have to work together and produce! Nobody likes them. The biggest “party” in America is those who call themselves independent. Gallup has the Democrats’ and Republicans’ favorability each at about 40%. Both parties are internally riven, warring and ideologically divided. Neither is as sure as it’s been in the past of its philosophical reason for being. Both have to prove they have a purpose. Otherwise they will in time go down, and it may not take that long.

Republicans announce their tax-reform plan, Sept. 27.

Both parties go forward as if they are operating in a pre-2016 reality. But the election, now almost a year ago, should have changed so many assumptions. For instance, when the Republican nominee promised not to cut entitlements, his crowds—Republicans, Democrats and independents—cheered.

Health-care reform this week went down, again. The Republicans did not have the votes in the Senate, again. How they tried to get the bills through suggests they are living in a dream. The dream was that once they held the House, the Senate and the White House, they would be able to call the shots, crush the foe, bully their way through. They thought they would finally be able to do what the Democrats did when President Obama and the Democratic Congress bullied through Obamacare.

That was a mistake. What the Democrats did shouldn’t be emulated.

Sen. John McCain, who basically killed the two Republican bills, did it based on a central insight as to the facts of the moment and the issue: The path to a new health-care law runs through the Democrats. The path to a bill better than ObamaCare—and it would have to be bad indeed to be worse than ObamaCare—runs through the Democrats. Changing one-sixth of the American economy cannot be successfully done without them. The American people will never accept a health-care law that is not backed by both parties. That means regular order—hearings, debate, negotiations—as Mr. McCain has said.

The Republicans failed because they tried to do what Mr. Obama, Speaker Nancy Pelosi and Majority Leader Harry Reid did, passing ObamaCare on a party-line vote. But bills that make great changes in how Americans live, such as Social Security and Medicare, must always have broad, two-party support. The Democrats pushed ObamaCare without fully understanding what the bill even contained. “We have to pass the bill so that you can find out what is in it,” said Mrs. Pelosi, mindlessly and in a way accurately: They were content to let regulators and administrators figure out the implications of everything.

But fierce pushback followed—the tea party uprising grew; the Democrats lost the House in 2010. Then came the failure in 2013 of the website on which the entire program depended, the admission by one of its architects that it was marketed to take advantage of “the stupidity of the American voter,” and the revelation that the central promise—“If you like your doctor you can keep your doctor”—was a lie.

The bill failed on its own terms, and it is still the law of the land. When Republicans tried to replace it, they tried to do just what the Democrats did—hold party-line votes on bills that few in the electorate fully understood. The difference is the electorate had previously been scalded. They’re not in a trusting mood.

Health care is experienced now as a fully national issue, and there are signs America is tilting left on it. (A bipartisan health-care bill might help blunt the coming movement for single payer.)

Democrats have to be part of fixing ObamaCare. And though they should be in a weak position, having lost the congressional majorities and the White House, they’re holding strong cards. The Republicans have crashed and burned twice, and there’s no reason to think they’ll magically succeed next time.

Health-care reform will have to come from both parties or it will not be accepted by America. It will have to be a compromise that comes from both parties or it will not pass the Kimmel test, the nonsensical but powerful showbiz bar such a bill must now clear. That means it will be more liberal than the Republicans want, and more expensive.

The Democrats will be hellish in negotiations. They will not call it “repeal and replace”; they’ll call it “repair and reinforce.” They’ll be demanding. And this is unjust. They caused the problem in the first place! They should be feeling chastened; they should be desperate to create a fix. Instead they’ve been amusing themselves watching the hapless Republicans blow it again. They should amuse themselves less.

Now the Republicans turn to tax reform. Again they move from a weakened position. They’re going forward without the momentum of victory, without the confidence of recently demonstrated skill. As he unveiled the plan this week, Speaker Paul Ryan wore a weirdly triumphant smile. “Today,” he said, “we are taking the next step to liberate Americans from our broken tax code.” He compared this moment to 1986, when Ronald Reagan won tax reform. But that was another world—a broadly popular president, both parties strong, each working, however reluctantly, with the other.

As strange as Mr. Ryan’s enacting of a happy warrior’s joy was the Democrats’ response. They reverted to their own antique playbook, taking potshots, being unserious. The Republican plan is “a massive windfall for the wealthiest Americans,” said Minority Leader Chuck Schumer. “It seems that President Trump and Republicans have designed their plan to be cheered in the country clubs and the corporate boardrooms.” It should be called “wealth-fare.” Sen. Bernie Sanders said the plan is “morally repugnant and bad economic policy.”

But the tax code is too big and too complicated, as Mr. Ryan said. It would do the country good to see it improved.

Both parties are breaking and broken. They both need a win. They could recover some of their standing with a bipartisan victory. It would show America the two-party system itself can win and produce something needed. This would reinforce the position of both parties. It would suggest they’re needed! If they can’t produce something big together, more Americans will become certain they are not.

Meanwhile, thousands of K Street tax lobbyists will be crawling the halls trying to affect the shape of the bill for their clients.

Everyone is acting as if they don’t know what time it is, or what position they themselves are in.

America is in trouble, with huge problems. The people need improvements in health care, in the tax code. They’re desperate for is a sense that improvement is actually possible.

This is no time for Democrats to be small, tatty and cheap, to do the old class warfare, to issue one-liners instead of thoughts. They should wake up and get serious.